Ranging behaviour and socio-biology of Eurasian otters (Lutra lutra) on lowland mesotrophic river systems

Néill, Lughaidh Ó; Veldhuizen, Tijmen; Jongh, Addy de; Rochford, John

doi:10.1007/s10344-009-0252-9

Cited by 24 publications

(12 citation statements)

References 19 publications

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“…A reintroduced otter population in the north‐east Iberian Peninsula followed a similarly rapid expansion, with 23 liberated animals occupying more than 300 km of rivers and streams only 2 years after being released (Saavedra, 2002). Rapid spread of otters in newly colonized areas and areas of reintroduction can be related to the availability of high‐quality habitats but also to the release from intra‐specific interactions, which play a major role in the use of space by otters (see Ó Néill et al. , 2009).…”

Section: Discussionmentioning

confidence: 99%

Natural, human and spatial constraints to expanding populations of otters in the Iberian Peninsula

Clavero

Hermoso

Brotons

et al. 2010

Journal of Biogeography

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Aim To determine the relationships between otter (Lutra lutra) distribution dynamics and environmental and spatial constraints over a 20‐year period. Location Andalusia, southern Iberian Peninsula. Methods We synthesized otter distribution data from three otter surveys (1985, 1995 and 2005) using subcatchment areas defined by hydrological barriers. Subcatchments were characterized by two ‘natural’ (climatic and orographic variables) and two ‘human’ (land use and population density) gradients. In addition, we calculated two contagion variables (the distance to previously occupied subcatchments and the percentage of occupied subcatchments within a 50 km buffer) for consecutively surveyed subcatchments. Results Between 1985 and 2005 the percentage of subcatchments with otters present increased from 42% to 72%. Otters tended to be rare or absent from human‐dominated areas. Anthropogenic gradients were better predictors of otter distribution than natural ones. Human and natural gradients showed strong covariation, but for any value of the natural gradients otters tended to be present in subcatchments with lower human impacts. Colonization of new subcatchments was found to be strongly related to contagion variables and expansion rates were slower than those estimated in other studies. Newly colonized areas tended to be located in areas with intermediate human influence, while repeated absences occurred mainly in areas where human impact was most severe. Main conclusions Our results suggest that recent otter expansion across Andalusia is a reflection of large‐scale improvement in environmental conditions. Otter populations that survived the period of strong and generalized declines appear to be acting as sources from which neighbouring areas are colonized, probably aided by improved water quality and increases in food availability. However, the further expansion of otters into their full original range is likely to be constrained by human‐impacted landscapes.

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Section: Discussionmentioning

confidence: 99%

Natural, human and spatial constraints to expanding populations of otters in the Iberian Peninsula

Clavero

Hermoso

Brotons

et al. 2010

Journal of Biogeography

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“…Furthermore, Eurasian otter are considered to have the widest distribution of all 13 otter species (Yoxon & Yoxon, 2019), with large home ranges, broad trophic niche breadth, and the ability to exploit multiple food resources, including those of terrestrial origin. For instance, a 3-month Irish telemetry study observed a mean home range of 7.5 AE 1.5 km (mean AE SD) for females occupying mesotrophic rivers and a home range of 13.2 AE 5.3 km for males occupying rivers of various productivity (mesotrophic and oligotrophic) (Ó Néill et al, 2009). Therefore, it is highly likely that spraints collected in a given area may not contain microplastics or even prey collected and ingested from that area, with some coastal spraints (e.g., Achill Island and Killary fjord) also possibly containing marine species, which could not be determined following the microplastic isolation process.…”

Section: Discussionmentioning

confidence: 99%

Microplastics in Eurasian otter (Lutra lutra) spraints and their potential as a biomonitoring tool in freshwater systems

et al. 2022

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The ubiquitous nature of microplastics in aquatic ecosystems may have serious implications for aquatic biota. While microplastic research in freshwater ecosystems is increasing, very few studies have assessed the physical presence of microplastics among top predators. The Eurasian otter (Lutra lutra), a top predator of aquatic ecosystems, is one of the most widely distributed otter species and has a broad habitat niche. The opportunistic collection of otter spraints (i.e., feces) presents a valuable opportunity to assess pollutants of freshwater ecosystems through noninvasive means. Here, we assessed the prevalence, abundance, and concentration of microplastics (100 μm to 5 mm), as well as dietary remains, in 53 spraint samples collected over eight river catchments spanning three regions of Ireland. We found microplastics present in 57% of spraints at an abundance of 1.2 ± 0.1 microplastics (MPs)/spraint (mean ± SE) and a concentration of 3.8 ± 0.6 MPs/g (dry weight). Fibers were the dominant particle type recovered (85%), followed by film (10%). No significant differences in microplastic concentrations were detected between the three regions assessed, or between spraints collected from areas upstream (i.e., “lower” exposure) or downstream (“higher” exposure) of putative microplastic sources, which were defined using spatial vector data. While microplastic concentrations were not explained by spraint condition (i.e., fresh, drying, or dry), spraints collected in autumn had a significantly higher concentration than spring and summer. Furthermore, microplastic abundance or concentration could not be linked to dietary composition based on the items identified. From a trophic perspective, this study showed that the presence of microplastics in the feces of otter is most likely being obtained through its prey (i.e., secondary ingestion). While there may be limitations associated with using spraints as a biomonitoring tool for microplastics in freshwater systems, particularly with respect to otter home range and dietary niche breadth, they could still be employed for a regional assessment of microplastic levels.

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“…As such, the only fish likely to be able to eat an Atlantic salmon smolt and move that far inland are sea trout ( Salmo trutta ). It is also important to note that otters’ home ranges tend to remain below 20 km (Erlinge, 1967; Néill, Veldhuizen, de Jongh, & Rochford, 2009) and, as such, it is unlikely that the three tags which moved more than 20 km upstream were ingested by otters. Ultimately, further research would be required to be able to individually identify the predator(s) responsible for these upstream movements.…”

Section: Discussionmentioning

confidence: 99%

Atlantic salmon living on the edge: Smolt behaviour and survival during seaward migration in River Minho

Flávio

Caballero

Jepsen

et al. 2020

Ecology of Freshwater Fish

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The Atlantic salmon (Salmo salar) population of the River Minho represents the southern natural distribution edge of the species. In line with the general trend for Atlantic salmon, this population has been declining over the years and is now at a critically low level. With river connectivity compromised by a large dam just 80 km upstream the River Minho's outlet, and an expected deterioration of climatic conditions, it is urgent to increase our knowledge of this population and identify survival bottlenecks that can be addressed. In this study, we used radio and acoustic telemetry to track Atlantic salmon smolts during their migration towards the sea and record both survival rates and possible causes of mortality. The recorded survival for the tagged migrating Atlantic salmon remained below 55% in the three studied years, indicating that the in‐river loss of smolts is likely a strong constraint to this population. From the smolts to which a likely cause of mortality could be attributed (34%), most appear to have been removed from the river (25%), with two confirmed events of bird predation and one of mammal predation. Interestingly, eight tags were recorded moving back upstream, likely indicating predation by larger fish. Increasing predator populations (e.g. cormorants, Phalacrocorax carbo) and invasive predators (e.g. American mink, Neovison vison) lead to elevated predation pressure on this already strained Atlantic salmon population, and further studies quantifying their impact in more detail could prove crucial for future management considerations.

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Ranging behaviour and socio-biology of Eurasian otters (Lutra lutra) on lowland mesotrophic river systems

Cited by 24 publications

References 19 publications

Natural, human and spatial constraints to expanding populations of otters in the Iberian Peninsula

Natural, human and spatial constraints to expanding populations of otters in the Iberian Peninsula

Microplastics in Eurasian otter (Lutra lutra) spraints and their potential as a biomonitoring tool in freshwater systems

Atlantic salmon living on the edge: Smolt behaviour and survival during seaward migration in River Minho

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